Background <p>Salinity stress poses significant challenges to viticulture by impairing plant growth and compromising fruit quality. The stress-mitigating properties of salicylic acid (SA) are well documented across various crops. However, the ability of SA to mitigate salinity stress in grapes and its potential underlying mechanisms remain unexplored. In this study, we systematically evaluated the efficacy of SA priming with various concentrations in alleviating NaCl-induced salinity stress in ‘Shine Muscat’ (<i>Vitis vinifera × Vitis labrusca</i>) grape seedlings and explored the physiological and biochemical responses underlying SA-mediated salinity stress mitigation.</p> Results <p>SA pretreatment significantly alleviated salt-induced growth inhibition and leaf damage, with the most pronounced mitigation effects occurring at 1.5 mmol/L concentration. Physiological analyses revealed that SA application effectively maintained photosynthetic efficiency under salt stress, especially by downregulating the expression of the chlorophyll degradation-related gene <i>VviPUB19</i>. SA enhanced the antioxidant defense system by increasing the activities of key enzymes, including superoxide dismutase (SOD) and catalase (CAT), thereby limiting the accumulation of superoxide anion (O₂·⁻) and malondialdehyde (MDA). Concurrently, SA upregulated the expression of antioxidant-related genes (<i>VvMAPK9</i>, <i>VvMKK2</i>, <i>VvMKK4</i>). In addition, SA priming improved osmotic adjustment, as evidenced by increased accumulation of soluble protein (SP), proline (Pro) and soluble sugar (SS), as well as mediated ionic homeostasis by promoting the absorption of K⁺, Mg²⁺, and Ca²⁺ and decreasing the uptake of Na⁺, which was supported by elevated expression of osmoregulatory genes (<i>VvKSC11-2</i>,<i> VvMYBA6</i>,<i> VvBES1-3</i>) and inorganic ion transport-related genes (<i>VaCPK21</i>,<i> VvNHX1</i>). Phytohormonal profiling revealed that SA application enhanced the levels of growth-promoting hormones, including auxin (IAA), gibberellin (GA₃), and zeatin riboside (ZR).</p> Conclusions <p>Collectively, our findings demonstrate that SA priming significantly enhances NaCl-induced salinity tolerance in grapevines by integrating photosynthetic machinery, antioxidant defense, osmotic balance, ionic equilibrium and hormone signaling, which provides a basis for employing SA as an effective and promising strategy to mitigate salinity stress in grapevine cultivation.</p>